Pipettes are used in the laboratory for the dosage of liquids. They are known in different forms of realisation. Air cushion pipettes have an integrated cylinder with, a plunger arranged therein. The cylinder is connected to an opening in an attachment neck via a channel. A pipette point is detachably connectable with the attachment neck. Sample liquid is aspirated into the pipette point or ejected from it by displacing the plunger in the cylinder. In doing so, plunger and cylinder do not come into contact with the liquid, because the plunger moves the liquid indirectly via an air cushion. Only the pipette point, which is generally made of plastic material, is contaminated and can be exchanged after use.
Direct displacement pipettes are detachably connected to a syringe, the plunger of which is drivable through the pipette, in order to aspirate sample liquid directly into the syringe and to eject it out from the latter. Because the syringe is contaminated with the sample liquid, it can be replaced. The syringe is also generally made from plastic material.
When pipetting, the pipette gives off the liquid picked up by the point or syringe in one step. When dispensing, the liquid picked up by the syringe or point is given off in small partial amounts.
Pipettes with several channels have several channels by means of which dosage takes place simultaneously. Pipettes can be realised as hand-held devices and/or as stationary devices.
Manual pipettes have an actuation button, which is connected directly or via a gear with the plunger in a cylinder, or another displacement equipment for an air cushion or sample liquid. Working with manual pipettes is fatiguing. In electronic pipettes, an electric drive motor is coupled to a displacement equipment via a gear. The user controls the functions of electronic pipettes via key entry. As a consequence, working with electronic pipettes is less fatiguing. However, the operation needs acquaintance to be used by the user of manual pipettes. Particularly, there is no actuation of a control button which is synchronised with the movement of the displacement equipment.
Departing from this, the present invention has the objective to provide a pipette which makes possible a less fatiguing work, while the handling of a manual pipette is maintained as far as possible.